The present invention relates to dental syringes, and more particularly to a dental syringe with a handle adapted to pre-heat water from a supply hose before it is delivered through the syringe tip into a patient's mouth.
Dental syringes are widely used by dentists, dental hygenists, dental assistants and the like. They are hand-held instruments which deliver water and air into a patient's mouth for washing and drying purposes. One such dental syringe is disclosed in U.S. Pat. No. 3,698,088. It includes a head, a handle coupled to the head, an elongate discharge tip, and a coupling for mounting the tip on the head. Supply hoses for air and water extend through the handle and are connected to the head. Valves in the head are selectively hand operated to discharge water, air, or both through the distal end of the tip.
Patient comfort is a very important objective in modern dentistry. The delivery of cold water into a patient's mouth during treatment can be discomforting when the patient's teeth or gums are sensitive to sudden changes in temperature. This is especially so when, for example, a hygenist is scaling plaque off of the teeth below the gum line. Even when local or general anesthetic has been used, e.g. during the performance of certain dental surgical operations such as a root canal, exposed tissues and nerve endings may be subjected to thermal shock if washed with cold water.
Therefore it is desirable to pre-heat the water before it is delivered into the patient's mouth. However, the water must not be too hot or similar undesirable effects will result. Lukewarm water at or near body temperature is preferred.
Heretofore, a number of apparatus have been developed for supplying warm water through a dental syringe. One apparatus included a remote water reservoir or tank, a heater element in the tank, a thermostat for regulating the temperature of the water in the tank, and a pump for pumping water from the tank through a water supply hose to a dental syringe. However, the water supply hose must be at least several feet in length in order for the syringe to be easily manipulated. The water cools while in the hose. Since the syringe is operated to deliver water intermittently, water frequently stands in the supply hose. The longer it stands, the more it cools. This problem has been alleviated somewhat by continuously recirculating the water, however such a design has necessitated the use of an additional water supply hose. In addition, it has been difficult to regulate the temperature of the water delivered with this design. The temperature fluctuates depending upon the length of the water supply hose and the amount of heat dissipated therefrom.
Another apparatus included a heater wire which runs the length of the water supply hose. The heater wire must either be mounted externally of the hose or embedded therein during the extrusion of the hose. High production cost has been a principal drawback of this design.
Yet another apparatus included an electric heater element in the head of the dental syringe which keeps the head warm. The shortcoming of this design is that only the initial squirt of water discharged from the syringe is warm, having stood in the head a sufficient length of time to be pre-heated to the desired temperature.